144 



ing ; posterior whorls flat or slightly convex, with a row of 

 uodulations at the anterior suture ; anterior whorls tabulate, 

 the posterior slope very wide, upward inclined, the anterior 

 slope narrow and contracted at the suture, roundly plicated, 

 the plicas terminating at the keel in obtuse nodulations. Last 

 whorl ventricose in the middle, slightly sloping from the keel 

 for a distance equal to the length of the posterior slope, thence- 

 suddenly contracted in a long, rather wide, curved, and slightly 

 reverted canal ; the transverse plications do not extend on tO' 

 the base, and are absent in the anterior-fourth of the whorl ;. 

 there are 14 nodulations on the last whorl. 



The whole surface is ornamented with crowded depressed, 

 rounded spiral threads, alternately large and small, crossed 

 by curved lines and striae of growth which obscurely crenulate 

 the lira?. 



Aperture large, oval ; outer lip slightly dilated anteriorly, 

 and slightly ascending posteriorly, smooth within ; inner lip' 

 widely spreading over the columella and decurrent on th& 

 inner face of the canal ; columella slightly concave above the 

 pillar. 



Length, 98 ; breadth, 48 ; length of aperture and canal, 73. 



Locality. — IJpper beds at Muddy Creek. (J". Dennant I) 



GENrs SiPHO. 



STN-OPSIS OF SPECIES. 



Aperture variced ; without costae, 1. S. lahrosus. 



Aperture simple. 



Ornament of granular rows ; no costae. 



2. S. crehrigranosus. 

 Ornament of flat equal threads ; costated. 



3. S. styliformis. 

 Ornament of round threads, alternately large and 



and small and transverse lamellae, with or without 

 costge. 4. S. asperulits, 



1. Sipho labrosus, spec. woy. ' Plate iii., fig. 7. 



Shell linear - lanceolar - fusiform, thin, of five and a half 

 whorls, ending in a large blunt mamillary apex of one and a 

 half globose smooth whorls. The other whorls convex, separ- 

 ated by a deep suture, ornamented all over with encircling 

 lir^e (ten on the penultimate whorl) alternately stout and 

 slender, crossed by angular threads raised into subgranular 

 imbrications on the lirae. 



Last whorl gradually attenuated into the^ long, slightly 

 curved and reverted, open canal ; the outer lip is thickened by 

 a varix slightly removed from the edge, varix somewhat 

 anovular and insinuated at the suture. 



